Effect of Whisker Content on Mechanical Properties and Microstructure of Hydroxyapatite-SiCw Composite Bioceramics

Abstract:

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Theory calculation result indicates that the maximal critical content of SiCw in
hydroxyapatite-SiCw composite bioceramics is 23.7%. Hydroxyapatite-SiCw composite micropowder was synthesized using in-situ composite method, and hydroxyapatite-SiCw composite bioceramics with different content of SiCw were produced by hot pressing sintering method. The microstructures of the materials were analyzed by SEM, and the mechanical properties were tested. The results show that the mechanical properties of composite material are the best when the whisker content is 20~23.7%.

Abstract: Effect of whisker orientation on mechanical properties of hydroxyapatite-SiCw composite
bioceramics was studied in this paper. Experiment results show that the mechanical properties of the
material are the best when the tensile stress acted on the composite material is parallel with the hot
pressing plane or the shearing stress is normal to the hot pressing plane, and they are the worst
when the tensile stress acted on the composite material is normal to the hot pressing plane or the
shearing stress is parallel with the hot pressing plane. This will offer great guidance for practical
applications of the hydroxyapatite-SiCw composite bioceramics.

Abstract: Hydroxyapatite is a kind of ideal biomaterials for bone and teeth replacement, but its low
strength and brittleness need to improve. As bone replacing materials, hydroxyapatite (HAP) and
zirconia both have advantage and disadvantage. Nano-sized HAP-ZrO2 powders and HAP-TZP (3Y)
(3mol% yttria - stabilized cubic zirconia) bioceramic for artificial joint have been fabricated in this
paper. The nano-sized HAP-ZrO2 powders with homogeneous distribution could be synthesized by
two-step precipitation method. The HAP-TZP bioceramic with small grain size could be obtained by
using hot-press sintering technology, and the sintering parameters are: sintering temperatures
T=1300°C, sintering pressure p=30MPa and sintering time t=30min. The mechanical properties,
microstructures and fracture pattern that were analyzed by SEM and optical microscopy of the
HAP-TZP bioceramic were investigated systematically. The results show that no reaction between
HAP and ZrO2 powders, which could be attributed to the very short sintering time of hot press
sintering.

Abstract: The influence of whisker orientation on machining mechanism, material removal rate
and roughness of finished surface when machining the hydroxyapatite /SiCw composite bioceramics
material using ultrasonic machining technology was studied. The research results show that material
removal rate and roughness of finished surface increase with the increase of the direction angle θ .
Under the same machining condition, the higher is the fracture toughness of the material, the lower
the material removal rate is. This provides basis for the ultrasonic machining of hydroxyapatite
/SiCw composite bioceramics material.

Abstract: The present work is on the synthesis of forsterite (Mg2SiO4) powder using talc and magnesium oxide powders as the starting materials followed by a heat treatment process. Sintering behavior and mechanical properties of the forsterite bodies were evaluated from 1200°C to 1500°C. Forsterite phase were detected in samples without any secondary phases at all sintering temperatures. A very high fracture toughness of 4.9MPa.m1/2 and Vickers hardness of 7.1GPa were measured for samples sintered at 1400°C, thus indicating the viability of this ceramic for biomedical application.